No surprise really, the logistical, cognitive, and self motivation, abilities of half the people asking about this visa stuns me. Therefore charge them max for babysitting, picture book stories, and spoon feeding.
Too much information. You need to show 500K, you need to provide your company registration and tax return/info, you need to show sole proprietorship, you need to write a company letter for yourself authorizing remote/freelance work and possibly why Thailand is suitable.
The good thing about Vientiane is it's a walk-up/in person consulate, so they won't take the fee if the paperwork is not sufficient. You can write a brief cover letter explaining it's a new company as well as show the company registration paperwork to support that.
it's quite common over the years that for various visa applications using the e-visa system the visa didn't arrive in time for the applicants flight, and so the applicant arrived using visa exempt and upon visa approval did a bounce. All I'm saying is that a consulate may choose to impose a requirement.
You simply need to provide proof of where you currently are, which should be somewhere in the country you are applying in. So in your home country it could be a driver's license or utility bill or something like that, if you're in a foreign country while you're applying then you would show your entry stamp or Visa or hotel booking